First thing you better do before anything else is do a compression check on that engine. Unless I missed that you have already done it. Before you sink any more money into it.

+1

Also given the lack of honesty of the seller I would be suspicious of the replaced transmission. Probably something cobbled together that could give you more problems down the road. Since the frame and deck were painted it might be a good idea to look those over carefully for damage as well. Maybe a good idea to pay a repair shop to look at what you have and what it might cost in total repairs.

The dishonesty of people always amazes me. How much easier life would be if people could just be honest and kind to one another.

To me it really sucks when people do this crap, they should just be up front and be honest and tell you what's wrong with it, so you not pulling your hair out trying to figure it out. No better than a thief in my opinion. But live and learn.

Thanks for the link. I already posted there already, and was advised the following:

LOL!! He was pretty blunt, but he is right. I was thinking the same thing, but just did not have the heart to tell you! The Diesel in the fuel sounded really strange.

First things first. I would take it to a small engine shop and see if the engine is good or not. As Popeye said, they can do a compression check and tell you what you have and then go from there! If the idiot did put diesel in the fuel, the engine may still be good! It may be that the plug is fouled and diesel fuel would certainly smoke.